The invention relates to a pyrotechnical actuator for a vehicle safety system in accordance with the preamble of claim 1. The invention further relates to an actuator assembly, a vehicle safety system as well as a method of actuating an actuator. A pyrotechnical actuator in accordance with the afore-mentioned type is known, for example, from U.S. Pat. No. 3,354,634 A1.
The known actuator comprises a cylinder and a hollow piston, the hollow piston and the cylinder being movable relative to each other. The hollow piston includes a distal slotted end portion which in the idle state of the actuator projects in a longitudinally axial direction from one axial end of the cylinder. For this purpose, at the axial end of the cylinder a land guided within the slotted end portion of the hollow piston is provided. Inside the hollow piston an igniter is arranged. The igniter is connected to the hollow piston and contains propellant charge which after ignition releases propellant gas. The released propellant gas causes an increase in pressure inside the hollow piston, thus causing the hollow piston to be displaced in the longitudinally axial direction inside the cylinder. Especially the hollow piston is displaced into the cylinder so that the total length of the actuator is reduced after activation. In other words, the overall length of the known actuator is larger in the idle state than in the activated state.
The relatively large overall length in the idle state is a problem in view of mounting of the actuator into an automotive vehicle. There is a trend towards ever more compact vehicles including increasingly complex technical equipment. The construction space available in a modern vehicle is limited in this respect. Consequently, there is a basic need for compact subassemblies for being mounted in a vehicle.